Ethernet link transmit power method based on on-chip detected alien crosstalk feedback

ABSTRACT

A method of operating an Ethernet transceiver includes initializing the Ethernet transceiver during a training mode of operation by monitoring background link operating characteristics with on-chip circuitry during a non-data-transfer interval to establish a baseline alien crosstalk value. Training data is then transmitted at a first transmit power level and first data rate to a link partner during a data transfer interval. The link is monitored with the on-chip circuitry during the data transfer interval to detect feedback indicating alien crosstalk effects to neighboring Ethernet links due to the transmitting. The first data rate and/or first transmit power level is then adjusted to an adjusted second data rate and/or second transmit power level based on the feedback. The Ethernet transceiver is then operated in a normal data transfer mode utilizing the adjusted second data rate and/or transmit power level.

RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/554,023, filed Aug. 28, 2019, entitled ETHERNET LINK TRANSMIT POWERMETHOD BASED ON ON-CHIP DETECTED ALIEN CROSSTALK FEEDBACK, which isexpressly incorporated by reference herein.

TECHNICAL FIELD

The disclosure herein relates to electronic communications, and moreparticularly to mitigating interference in signals transmitted overcommunication channels.

BACKGROUND

Communication systems are widely used in computer and device networks tocommunicate information between computers and other electronic devices.Transceivers of a communication system send and receive data over a link(including one or more channels) of a communication network tocommunicate with other transceivers. A transceiver includes atransmitter for sending information across a link, and a receiver forreceiving information from a link. The receiver detects transmitted dataon the link and converts the data into a form usable by the systemconnected to the transceiver. For example, one widely-used networkcommunication standard is Ethernet, including several differentstandards for different network bandwidths, including 10 GBASE-Tallowing 10 gigabit/second connections over unshielded or shieldedtwisted pair cables. A similar standard, NBASE-T, provides for reduceddata rates on the order of 1 Gbps, 2.5 Gbps, 5 Gbps and 10 Gbps.

There are multiple sources of impairment and interference in a 10GBASE-T system which can cause significant performance degradation.These sources of impairment and interference can be broadly categorizedas internal and external sources. The internal sources are often causedby the link-partners themselves and imperfect channel characteristics.Examples of these sources are inter-symbol interference (ISI), echo andpair-to-pair cross-talk such as far-end crosstalk (FEXT) and near-endcrosstalk (NEXT). Such noise sources are typically known to the linkpartners and thus can often be cancelled effectively with cancellers andequalizers.

Another type of impairment in 10 GBASE-T systems is interference fromsources external to a particular link. Examples of external interferingsources, referred to herein as alien interferers, include adjacentcross-talking Ethernet ports/links, where the noise source is from adifferent port or cable that is adjacent to the subject link (port). Insuch circumstances, the source of the interference is unknown to thesubject link, and is a greater challenge to reduce than noiseoriginating from a known source such as ISI, echo, FEXT, and NEXT.

When adding new Ethernet links, conventional standards typically providefor transmit power settings based on the received signal power from theother side of the link which is a function of the length of the link. Noprovisions are generally made for any alien crosstalk effects the newlink may have on existing links. Accordingly, what is needed are systemsand methods that minimize any alien interference impact to existingEthernet links due to expansion of one or more a networks to include newlinks.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure are illustrated by way of example, and notby way of limitation, in the figures of the accompanying drawings and inwhich like reference numerals refer to similar elements and in which:

FIG. 1 illustrates one embodiment of an Ethernet network architecture.

FIG. 2 illustrates one embodiment of an Ethernet link that may be usedin the network architecture of FIG. 1.

FIG. 3 illustrates a block diagram for one embodiment of an Ethernet PHYarchitecture.

FIG. 4 illustrates a state diagram for one embodiment of a generalizedmethod of operating an Ethernet link through various autonegotiation,training, and normal data operating modes.

FIG. 5 illustrates a state diagram for one embodiment of a method ofestablishing a link transmit power setting based on feedback fromneighboring links as detected by a newly installed Ethernet PHY.

FIG. 6 illustrates a state diagram for an alternative embodiment forestablishing a link transmit power setting similar to FIG. 5.

FIG. 7 illustrates a flowchart for a further embodiment of a method ofestablishing a link transmit power setting based on feedback collectedby a network device.

FIGS. 8 and 9 illustrate respective flowcharts for embodiments of amethod of establishing a link transmit power setting similar to FIG. 7.

DETAILED DESCRIPTION

Embodiments of Ethernet networks, links, transceivers and associatedoperating methods are disclosed. For one embodiment, a method ofoperating an Ethernet transceiver includes initializing the Ethernettransceiver during a training mode of operation by monitoring backgroundlink operating characteristics with on-chip circuitry during anon-data-transfer interval to establish a baseline alien crosstalkvalue. Training data is then transmitted at a first transmit power leveland first data rate to a link partner during a data transfer interval.The link is monitored with the on-chip circuitry during the datatransfer interval to detect feedback indicating alien crosstalk effectsto neighboring Ethernet links due to the transmitting. The first datarate and/or first transmit power level is then adjusted to an adjustedsecond data rate and/or second transmit power level based on thefeedback. The Ethernet transceiver is then operated in a normal datatransfer mode utilizing the adjusted second data rate and/or transmitpower level.

FIG. 1 illustrates one embodiment of an Ethernet network architecture,generally designated 100. A network device such as a network switch 102interfaces with a general purpose computer 104 via an interface circuit106. The computer may be local to the network, or remote, such that thenetwork switch may be controlled via Information Technology (IT)personnel. For one embodiment, the computer executes instructionsassociated with network applications, including diagnostics software,that are stored in memory 108. The diagnostics software provides amethodology for the network switch to carry out diagnostic processesinvolving, for example, crosstalk and transmit power determinations,more fully described below.

Further referring to FIG. 1, in one embodiment, the network switch 102includes multiple Ethernet ports 110 corresponding to individualEthernet links. The network switch may include, for example, forty-eightor more Ethernet ports to support an equal number of links. Each portconnects to a local end 112 of an Ethernet cable 114. The remote end 116of each cable connects to a network device 118, such as a computer,network printer, access node, or the like. Further details regardingeach Ethernet link are described below with respect to FIG. 2.

With continued reference to FIG. 1, for one embodiment, each Ethernetport 110 on the network switch 102 communicates to every other port viaa signal bus 120. Control logic 122 on the network switch couples to thesignal bus 120, and manages coordination between the circuits associatedwith each port. The network switch may also include an Internet port 124that provides Internet access to the various Ethernet links.

FIG. 2 is a block diagram illustrating one embodiment of an Ethernetlink that may be employed in the network of FIG. 1. The link includes afirst transceiver integrated circuit (IC) or chip 202 and a secondtransceiver chip 204 that can communicate with each other. The firsttransceiver 202 includes “transceiver components” including one or moretransmitters TX_(A)-TX_(A) and one or more receivers RX_(A)-RX_(D).Similarly, the second transceiver 204 includes various transceivercomponents including one or more transmitters TX_(E)-TX_(H) and one ormore receivers RX_(E)-RX_(H). The transmitters TX_(A)-TX_(H) shown inFIG. 2 can be considered individual “transmitters,” as typicallyreferenced herein, or can be considered individual transmitter channelswhich a transmitter block within the transceiver can independentlytransmit signals on. Similarly, receivers RX_(A)-RX_(H) can beconsidered individual “receivers,” as typically referenced herein, orcan alternately be considered individual receiver channels which areceiver block within the transceiver can independently receive signalson. The transmitters and receivers are connected to one or morecomponents (not shown) of a computer system, device, processor, or other“controller” (such as the network switch of FIG. 1) associated with eachrespective transceiver which wants to communicate data over thecommunication network. For example, the transmitters receive data andcontrol signals from the controller connected to the first transceiver202 in order to send the data over the network to other transceivers andcontrollers, while the receivers receive data from other transceiversand controllers via the network in order to provide the data to thecontroller connected to the first transceiver 202.

The first transceiver chip 202 can communicate with the secondtransceiver chip 204 over one or more communication channels of acommunication link 206. In one embodiment, such as one similar to the 10GBASE-T Ethernet standard, four communication channels are provided onthe communication link 206, each channel including a twisted pair cable.Thus, in that standard, there are four transmitters TX and fourcorresponding receivers RX provided in each of the transceivers 202 and204, each transmitter associated with one of the local near-endreceivers in the same transceiver, and each such transmitter/receiverpair dedicated to one channel used for duplex communication. Atransmitter/receiver pair in the first transceiver 202 communicatesacross a channel of the link 206 to a far-end transmitter/receiver pairin the second transceiver 204. A transmitter TX and a receiver RX thatare connected to the same channel/link, or two transceivers connected bythe communication link 206, are considered “link partners.”

An interface 208 can be provided in the first transceiver chip 202 andan interface 210 can be provided in the second transceiver chip 204 toallow data transmissions between the transceivers to be routed to theappropriate transceiver blocks. For example, the interfaces 208 and 210can include transformers, and circuitry used for directing signals ordata (alternatively, some or all circuitry can be included in othercomponents, such as transmitters TX and receivers RX).

In one example, from the point of view of the first transceiver chip202, data transmissions during a normal or regular operation mode from alocal transmitter TX are provided to the interface 208, which outputsthe data on a corresponding channel of the communication link 206. Thedata is received by the link partner, the second transceiver chip 204.The interface 210 of the transceiver 204 provides the received data toits receiver RX connected to that same channel. Furthermore, due tonoise effects such as near-end crosstalk and echo, the data transmittedby the transmitters is also received by the near-end receivers in thesame transceiver. Echo and crosstalk filters may be used to filter outthis noise so that the receivers receive only data from othertransceivers. In virtually all real scenarios, the data transmitted by alocal transmitter has no dependence or relation with data being receivedby the corresponding local receiver.

In many instances, enterprise applications that employ the channelarchitecture of FIG. 2 utilize thousands of such deployments, resultingin complex crosstalk environments. For instance, in many circumstancessuch as the network of FIG. 1, a commercial building or residenceemploys existing Ethernet cable throughout various walls and ceilings inorder to establish each link from a given remote location in thebuilding (such as a switch plate in a given office), to the centralizedlocation of the network switch. The original routing of the cables maybe such that one or more newly added cables may cause alien crosstalkinterference affecting one or more of the previously installed originalcables. This is shown in FIG. 1, at 126.

The Ethernet links of FIG. 2, which are employed in the network of FIG.1 operate at very high data rates, as high as 10 Gbps. Links that areexposed to alien crosstalk may not be able to operate at such high datarates, and may need to have their data rates reduced in order to have anacceptable signal-to-noise ratio (SNR) for data transfers. Such asituation is undesirable when installing new links.

FIG. 3 is a block diagram of one embodiment of an Ethernet physicalcircuit (PHY) architecture that minimizes the impact of crosstalk toneighboring links as a new link is installed for service in a givennetwork. The PHY architecture, generally designated 300, is employed foreach of the transmit/receive channels of each end of the link shown inFIG. 2. The PHY includes a digital signal processor DSP 302 thatincludes various adaptive filters that may be trained during trainingmodes of operation to generate filter coefficients for minimizingnear-end and far-end crosstalk, as well as echo effects along the link.For one embodiment, the DSP may include an input to receive parameterinformation relating to other links coupled to the network device orswitch (such as switch 102 in FIG. 1). Along a transmit path of the PHY,a digital-to-analog converter (DAC) 304 acts as a transmit driver andgenerates analog output signals for transmission along a transmissionline 306 via hybrid circuitry 308. A receive path of the PHY includes areceiver front end circuit 310 that receives incoming signals via thehybrid circuit 306, and provides the received signals to ananalog-to-digital converter (ADC) 312. The digitized signals are thenfed to the DSP for filtering, equalization, and so forth.

For situations involving installation of a new link into an existingnetwork, one embodiment of the PHY architecture employs training logicin the form of alien performance detection circuitry 314 to generatefeedback relating to any effects on other links arising from operationof the new link. The alien performance detection circuitry may includesignal-to-noise ratio (SNR) measurement circuitry 316 to determinerespective SNR values for one or more adjacent links to the new link,and cross talk measurement circuitry 318. The crosstalk measurementcircuitry detects crosstalk effects to adjacent links, and can comparethe detected crosstalk to a pre-programmed threshold level or topreviously detected levels of crosstalk. Crosstalk information may befed to the crosstalk measurement circuitry from the output of the ADC312 and/or the DSP 302. The DSP may be able to provide crosstalkinformation in situations where echo from transmission may hide aliencrosstalk information that might otherwise be available from the ADC312. Measurements made by the SNR measurement circuitry 316 and/or thecross-talk measurement circuitry 318 may be fed to a control statemachine 320. As explained in further detail below, the control statemachine provides transmit power adjustments and/or data rate adjustmentsto the transmit DAC 304 based on the detected feedback, thus optimizingany adverse effects to existing links from the newly installed link.

To more fully understand the methods described below, it's helpful tounderstand a few basic operating modes for all of the links of a givennetwork. FIG. 4 is a state diagram illustrating one example of operatingan Ethernet link, generally designated 400. This example is suitable forNBASE-T and/or 10 GBASE-T Ethernet standards, but other differentconfigurations and types of transceiver components can be used in otherembodiments for other, different communication standards. Bringing up agiven link generally begins with an autonegotiation step, at 402, wherethe link partners communicate with each other using a low-speed and lowdata rate protocol to advertise common capabilities. Such capabilitiesmight involve rate downshifting, initial transmit power levels, and acommonly agreed-upon starting data rate. Following autonegotiation, thelink begins a training step, at 404, to transfer data between the linkpartners at the agreed-upon transmit power level and data rate togenerate a certain level of filter adaptations. If the training mode issuccessful, then the link enters a normal data mode of operation, shownat 406.

With continued reference to FIG. 4, should the link training mode failless than a predetermined threshold number of times N, then theautonegotiation step is restarted, at 402, followed by another linktraining step, at 404. If the link continues to fail more than thethreshold allowed, then the data rate may be reduced, at 408, and thelink returned to the autonegotiation mode 402 again. The threshold levelN may be programmable and based on the time allowed for autonegotiationoperations, training operations, and so forth.

In the event the link passes training, operates successfully for a givenperiod of time, then fails for some unknown reason, then a fast retrainmay take place, at 410, to restore the link to the normal data operatingmode. A fast retrain generally involves far fewer training steps toreturn the link to normal operation as compared to a full trainingsequence. In some embodiments, the fast retrain may be associated with aquiet period or other signature that may be detectable by other PHY's inthe network. In some circumstances, a fast retrain may not work torestore the link to a data operating mode. If this occurs, the link mayreturn to the autonegotiation mode 402 to re-initialize itself.

The general operating mode steps described above may be carried out atany time by any of the links operating in the network. Further, whethera given link is undergoing training or a fast retrain may be detectableby any other PHY, and/or the network switch due to the unique signaturesassociated with full training sequences and fast retrain sequences. Forexample, if the alien crosstalk measurement shows that there is a pausein crosstalk for a predetermined amount of time before the crosstalkbegins again, it may indicate a fast retrain.

Referring now to FIG. 5, one embodiment of a transmit power method basedon alien link parameters involves generating transmit power and/or datarate adjustments for a new link based on feedback from the aliencrosstalk measurement circuit 314. Different embodiments are describedbelow that approach the training of a new link in different ways.

Further referring to FIG. 5, a first embodiment of the transmit powermethod takes place during the previously-described training mode ofoperation. With a given PHY in the training mode, it listens online foralien crosstalk information for a predetermined amount of time to set abaseline alien crosstalk value, at 502. The PHY then transmits trainingdata at a maximum transmit power level of PO and at a maximum data rate,at 504. Following the training data transmission, the PHY listens onlineagain for any changes in the baseline alien crosstalk for apredetermined time, at 506. If there is a basic training failureassociated with the new link, then the process reverts back to theinitial training step at 502. If the basic training failures occur morethan a predetermined threshold number of times, then the state machinemay direct the PHY and link partner to operate at a lower data rate, at508.

At this point, assuming no training failure, and further referring toFIG. 5, the SNR measurement circuitry 316 (FIG. 3) and/or crosstalkmeasurement circuitry 318 (FIG. 3) in the PHY may or may not detectchanges in SNR and/or crosstalk. The control state machine may then makeone or more of the following adjustments based on any detected SNR orcrosstalk. For example, the crosstalk measurement circuitry may detectany one of a number of signatures indicating that one or more links maybe carrying out a fast retrain (such as by detecting a “pause”, or tone,or other indicator of a fast retrain). The state machine then maydial-down the transmit power to a level incrementally lower than theprevious level, at 510, and the process reverts back to the initialtraining step, at 502. In a similar manner, the alien performancedetection circuitry may detect that an existing link has completelydropped, due to, for example, no baseline level of crosstalk such asdetected earlier. In such a circumstance, the state machine may directthe transmit DAC circuitry to operate at a lower transmit power, at 512,and the new link training starts again at the first step 502. At somepoint, the new device completes training of the link, at 514, with anoptimized data rate and transmit power level that is not only optimalfor the newly installed link, but has little to no effects on thesurrounding links, thereby reducing the risk that the other links maydownshift to lower data rates and stay there.

FIG. 6 illustrates a state diagram similar to the one shown in FIG. 5,corresponding to a method of setting a transmit power level and datarate, but where the initial data rate and transmit power level are at aminimum level. With a given PHY in the training mode, it listens onlinefor alien crosstalk information for a predetermined amount of time toset a baseline alien crosstalk value, at 602. The PHY then transmitstraining data at a minimum transmit power level of PO and at a minimumdata rate of R0, at 604. Following the training data transmission, thePHY listens online again for any changes in the baseline alien crosstalkfor a predetermined time, at 606. If there is a basic training failureassociated with the new link that occurs less than a predeterminednumber of time N, then the process reverts back to the initial trainingstep at 602. If the basic training failures occur more than “N” time,then the state machine may direct the transmit DAC to operate at an evenlower data rate than R0, at 608.

Further referring to FIG. 6, should the initial training steps succeed,then the initial power backoff level and/or data rate may be increased,at 610 and 612, and the alien crosstalk detection steps repeated, at602-606. These steps may iterate several times until either the trainingsteps fail for the link in training, or a change in cross talk or SNR isdetected in any of the other links. For example, the crosstalkmeasurement circuitry may detect any one of the signatures describedabove indicating that one or more of the existing links may be carryingout a fast retrain (such as by detecting a “pause”, or tone, or otherindicator of a fast retrain). The state machine then may dial-down thetransmit power to a level incrementally lower than the previous level,at 614, and the process reverts back to the initial training step, at602. In a similar manner, the alien performance detection circuitry maydetect that an existing link has completely dropped, due to, forexample, no baseline level of crosstalk such as detected earlier. Insuch a circumstance, the state machine may direct the transmit DACcircuitry to operate at a lower transmit power, at 616, and the new linktraining starts again at the first step 602.

With continued reference to FIG. 6, at some point, the iterative stepsdescribed above lead to a state where training succeeds at a highestpower and data rate without a power or rate backoff. At that state, thenew link may exit the training mode of operation and enter the normaldata mode of operation, at 618.

The embodiments of FIG. 5 and FIG. 6 thus provide a mechanism for anEthernet PHY to detect feedback associated with crosstalk and/or SNReffects on adjacent links caused by operation of a new link. Whilebeneficial in many circumstances, there may be scenarios where the PHYarchitecture may not include SNR measurement circuitry or crosstalkmeasurement circuitry. Embodiments described below relating to FIGS.7-10 address situations where information associated with existing linksin a network provided by a service provider (such as via a networkdevice or switch) may serve as feedback that the PHY can use to adjusttransmit power and data rates for a new link in a manner that minimizesthe operational impact to existing links.

Referring now to FIG. 7, one embodiment of a link test method utilizingfeedback from a service provider involves first collecting a first setof various performance metrics of known neighboring channels, at 702.This may be straightforwardly carried out where adjacent links eachterminate locally in a common network device or switch. The performancemetrics may include baseline values of packet errors, average LDPCvalues, LDPC iteration counts, LDPC/CRC errors, SNR margins, powerbackoff levels, and so forth. At 704, a link attempt is initiated at ahighest target line rate for the new link. If the training issuccessful, at 706, then a second set of the performance metrics iscollected, at 708, and compared to the first set of performance metrics,at 710. The method is completed, at 716, if the training for the newlink is successful (at 706), and any impacts to neighboring links areless than a predetermined threshold, at 712. If the training is notsuccessful (at 706), or the impacts to other links are above thethreshold (at 712), then the process repeats, albeit with the EthernetPHY adjusted to transmit data at a lower data rate and/or transmit powerlevel, at 714.

The embodiment of FIG. 7 may be carried out quickly, and on the networkswitch side with little involvement from the Ethernet PHY. As a result,the Ethernet PHY may be either of a standardized design, or proprietarydesign.

FIG. 8 illustrates a further embodiment of a link test method similar toFIG. 7, but includes steps to avoid any performance impact to existingactive channels in the network. In the network switch, software monitorsthe performance metrics of known neighboring links. During theinitialization of a new link, the software enables a test mode for thenew link, at 802. The test mode involves gradually increasing thetransmit power level of the new PHY, at 804. The test mode ends, at 810,when a detected performance impact, at 806, is determined to meet orexceed a pre-determined threshold. A maximum power level is thenidentified for the new link, at 812. The link may then be establishedusing the determined maximum transmit power level, at 814. For oneembodiment, a highest data rate is utilized for the newly initiatedlink, at 816. If the link fails, at 818, then a lower data rate isutilized, at 820. If the link is successful, at 818, then the linktraining is complete, at 822.

The embodiment of FIG. 8 has relatively no impact to neighboringchannels, and no requirements pertaining to the PHY design.

FIG. 9 illustrates a flowchart of a link test method according to afurther embodiment that is similar to those described with respect toFIGS. 7 and 8. The method may be employed, for example, when a potentialsubscriber desires to determine a highest data rate possible from agiven service provider (SP). The method begins with the SP enabling atest mode for the target channel (to be added to the network), at 902.Once enabled, the target PHY may then utilize a protocol to enable thetest mode and monitor channel conditions of adjacent ports through ashared communication interface such as an MDC/MDIO bus, I2C bus, orother communication channel. The SP monitors the performance metrics ofneighboring channels sharing the same cable bundle, at 904. The metricsmay involve packet errors, SNR margin, LDPC iteration/average/errors,and power backoff through access to an MDIO interface. The test modecauses the new link PHY to increase a transmit power level for trainingdata at a specific time interval, at 906. The power level adjustment mayiteratively continue until an impact to neighboring channels isdetected, at 908. If an impact to neighboring channels above a thresholdis detected, then a stop command is issued to the PHY, at 910. The PHYthen automatically initiates the link at the highest data rate with thelast transmit power setting used when the stop command was received, at912. The PHY then continues training until the training succeeds, whichmay involve one or more iterations of determining training success, at914, and data rate downshifting, at 916, if the training isunsuccessful. Once the link is complete, at 918, then the target channelmay indicate a “Done” condition, and the service provider may retrievethe results, including recording the power backoff level and data rateof the link at 920. For some embodiments, the service provider mayfurther configure the link PHY to support the maximum data rate andpower backoff determined above.

In the foregoing description and in the accompanying drawings, specificterminology and drawing symbols have been set forth to provide athorough understanding of the present invention. In some instances, theterminology and symbols may imply specific details that are not requiredto practice the invention. For example, any of the specific numbers ofbits, signal path widths, signaling or operating frequencies, componentcircuits or devices and the like may be different from those describedabove in alternative embodiments. Also, the interconnection betweencircuit elements or circuit blocks shown or described as multi-conductorsignal links may alternatively be single-conductor signal links, andsingle conductor signal links may alternatively be multi-conductorsignal links. Signals and signaling paths shown or described as beingsingle-ended may also be differential, and vice-versa. Similarly,signals described or depicted as having active-high or active-low logiclevels may have opposite logic levels in alternative embodiments.Component circuitry within integrated circuit devices may be implementedusing metal oxide semiconductor (MOS) technology, bipolar technology orany other technology in which logical and analog circuits may beimplemented. With respect to terminology, a signal is said to be“asserted” when the signal is driven to a low or high logic state (orcharged to a high logic state or discharged to a low logic state) toindicate a particular condition. Conversely, a signal is said to be“deasserted” to indicate that the signal is driven (or charged ordischarged) to a state other than the asserted state (including a highor low logic state, or the floating state that may occur when the signaldriving circuit is transitioned to a high impedance condition, such asan open drain or open collector condition). A signal driving circuit issaid to “output” a signal to a signal receiving circuit when the signaldriving circuit asserts (or deasserts, if explicitly stated or indicatedby context) the signal on a signal line coupled between the signaldriving and signal receiving circuits. A signal line is said to be“activated” when a signal is asserted on the signal line, and“deactivated” when the signal is deasserted. Additionally, the prefixsymbol “I” attached to signal names indicates that the signal is anactive low signal (i.e., the asserted state is a logic low state). Aline over a signal name (e.g.,

) is also used to indicate an active low signal. The term “coupled” isused herein to express a direct connection as well as a connectionthrough one or more intervening circuits or structures. Integratedcircuit device “programming” may include, for example and withoutlimitation, loading a control value into a register or other storagecircuit within the device in response to a host instruction and thuscontrolling an operational aspect of the device, establishing a deviceconfiguration or controlling an operational aspect of the device througha one-time programming operation (e.g., blowing fuses within aconfiguration circuit during device production), and/or connecting oneor more selected pins or other contact structures of the device toreference voltage lines (also referred to as strapping) to establish aparticular device configuration or operation aspect of the device. Theterm “exemplary” is used to express an example, not a preference orrequirement.

While the invention has been described with reference to specificembodiments thereof, it will be evident that various modifications andchanges may be made thereto without departing from the broader spiritand scope of the invention. For example, features or aspects of any ofthe embodiments may be applied, at least where practicable, incombination with any other of the embodiments or in place of counterpartfeatures or aspects thereof. Accordingly, the specification and drawingsare to be regarded in an illustrative rather than restrictive sense.

1. (canceled)
 2. A method of operating an Ethernet transceiver disposedat one end of a link, the link located proximate to neighboring links,the method comprising: transmitting first data at a first transmit powerlevel and first data rate to a link partner during a data transferinterval; detecting feedback during the data transfer interval, thefeedback being indicative of crosstalk between the link and one or moreof the neighboring Ethernet links due to the transmitting; adjusting thefirst data rate and/or first transmit power level to an adjusted seconddata rate and/or second transmit power level based on the feedback; andtransmitting second data utilizing the adjusted second data rate and/ortransmit power level.
 3. The method according to claim 2, furthercomprising: prior to the transmitting, detecting background crosstalkbetween the link and one or more of the neighboring links during anon-data-transfer interval to determine background crosstalk; andwherein the feedback is indicative of the crosstalk between the link andone or more of the neighboring links in addition to the backgroundcrosstalk.
 4. The method of claim 3, wherein the transmitting first dataat the first transmit power level and first data rate further comprises:initially setting the first power level to a maximum power level and thefirst data rate to a maximum data rate.
 5. The method of claim 4,wherein the adjusting comprises: comparing the feedback to thebackground crosstalk; and reducing the first data rate and/or the firsttransmit power level based on the comparing.
 6. The method of claim 5,wherein the comparing and reducing further comprises: iterativelyadjusting the data rate and/or the transmit power level based oniterative comparisons of iteratively obtained feedback to the backgroundcrosstalk.
 7. The method of claim 2, wherein the transmitting first dataat the first transmit power level and first data rate further comprises:initially setting the first power level to a minimum power level and thefirst data rate to a minimum data rate.
 8. The method of claim 7,wherein the adjusting comprises: comparing the feedback to thebackground crosstalk; and increasing the first data rate and/or firsttransmit power level based on the comparing.
 9. The method of claim 8,wherein the comparing and increasing further comprises: iterativelyadjusting the data rate and/or transmit power level based on iterativecomparisons of iteratively obtained feedback to the backgroundcrosstalk.
 10. The method of claim 2, wherein: the detecting of thefeedback comprises detecting a signal indicative of alien crosstalkgenerated between the link and one or more of the neighboring links inresponse to the transmitting.
 11. The method of claim 10, wherein: thedetecting of the feedback comprises detecting a signal corresponding toa retraining sequence being carried out by the one or more of theneighboring links in response to the transmitting.
 12. An Ethernettransceiver, comprising: transmit circuitry configured to transmit firstdata at a first transmit power level and first data rate over a link toa link partner during a data transfer interval, the link being disposedin proximate location to neighboring Ethernet links; detection circuitryconfigured to detect feedback during the data transfer interval, thefeedback being indicative of crosstalk between the link and one or moreof the neighboring Ethernet links due to the transmitting of the firstdata; and control circuitry configured to adjust the first data rateand/or first transmit power level to an adjusted second data rate and/orsecond transmit power level based on the feedback and to configure thetransmit circuitry to transmit second data utilizing the adjusted seconddata rate and/or transmit power level.
 13. The Ethernet transceiveraccording to claim 12, wherein: the detection circuitry is configured todetect background crosstalk between the link and one or more of theneighboring links during a non-data-transfer interval to determinebackground crosstalk; and wherein the feedback is indicative ofcrosstalk between the link and one or more of the neighboring links inaddition to the background crosstalk.
 14. The Ethernet transceiveraccording to claim 13, wherein: the control circuitry is configured toinitially set the first power level and first data rate to respectivemaximum power and data rate values.
 15. The Ethernet transceiveraccording to claim 14, wherein the control circuitry further comprises:comparison circuitry configured to compare the feedback to thebackground crosstalk and to generate a comparison value; and wherein thecontrol circuitry is configured to reduce the first data rate and/orfirst transmit power level based on the comparison value.
 16. TheEthernet transceiver according to claim 13, wherein: the controlcircuitry is configured to initially set the first power level and firstdata rate to respective minimum power and data rate values.
 17. TheEthernet transceiver according to claim 16, wherein the controlcircuitry further comprises: comparison circuitry configured to comparethe feedback to the background crosstalk and to generate a comparisonvalue; and wherein the control circuitry is configured to increase thefirst data rate and/or first transmit power level based on thecomparison value.
 18. A network switch, comprising: multiple Ethernetports for coupling to respective multiple neighboring links, ones of themultiple Ethernet ports including: transmit circuitry configured totransmit first data at a first transmit power level and first data rateover a link to a link partner during a data transfer interval; detectioncircuitry configured to detect feedback during the data transferinterval, the feedback being indicative of crosstalk between the linkand one or more of the neighboring Ethernet links due to thetransmitting of the first data; and control circuitry configured toadjust the first data rate and/or first transmit power level to anadjusted second data rate and/or second transmit power level based onthe feedback and to configure the transmit circuitry to transmit seconddata utilizing the adjusted second data rate and/or transmit powerlevel.
 19. The network switch according to claim 18, wherein for ones ofthe multiple Ethernet ports: the detection circuitry is configured todetect background crosstalk between the link and one or more of theneighboring links during a non-data-transfer interval to determinebackground crosstalk; and wherein the feedback is indicative ofcrosstalk between the link and one or more of the neighboring links inaddition to the background crosstalk.
 20. The network switch accordingto claim 18, wherein for ones of the multiple Ethernet ports, thecontrol circuitry further comprises: comparison circuitry configured tocompare the feedback to the background crosstalk and to generate acomparison value; and wherein the control circuitry is configured toadjust the first data rate and/or first transmit power level based onthe comparison value.
 21. The network switch according to claim 18,wherein: the detection circuitry is configured to detect the feedback inthe form of at least one from the group comprising an indicator of aneighboring link fail and an indicator of a retraining sequence for aneighboring link.